The use of chlorophyll fluorescence measurements to examine photosynthetic performance and stress in algae and plants may be used in physiological and eco-physiological studies. Micro algae that grow in water may have a characteristic fluorescence signature. That signature may be altered if exposed to toxins. Fluorescence may also be used to study photosynthetic performance when coupled with noninvasive measurements such as absorption spectroscopy, gas analyses, and infrared thermometry. A microfluidic analytical device for an algal cytometer may be performed under a microscope. However, microfluidic cytometers generally use only one excitation light source and the output is voltage pulses as opposed to a time-resolved waveform for fluorescence intensity.